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Hi I have some servers with not too terribly demanding requirements other than uptime. I'm new to Ubuntu, having just left CentOS after ten glorious years and many more prior to that. 20.04 LTS seemed like the right way to go here, but I immediately ran into a need for a 5.10 kernel and 5.10.4 was current at the time. Time to clean up that mess as I have a need for some userspace tools that are kernel version locked.

One of the things I noticed is the kernels in Ubuntu LTS repos always seem to be x.y.0, such as 5.10.0. If I wanted to stay on 5.10, I'd be downgrading, and if I go with 5.11.0, I'm potentially inheriting new misfeatures in the .0 release, even if there are roll-up improvements on the previous minor releases.

Am I interpreting this correctly?

My intuition of the right upgrade path is to 5.11.0 (moving forward and not backwards), just want to understand this apparent quirk of LTS kernel support. Thanks!

Brian Topping
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Ubuntu markets its default Linux version as their "GA" kernel. GA stays on the same major version for the duration of that release's lifecycle, changes are small and backported. Same version lock as other packages, but Linux version determines supported hardware and OS features.

Kernel is unique in that there also are variant packages with other use cases and even other versions. From the Ubuntu kernel team, so reproducible builds, and support is available. "Hardware enablement" and "edge" are of particular interest:

  • generic-hwe Targets a later version of the upstream kernel, and updates with respect to that every 6 months until it matches the GA kernel in the subsequent LTS release.
  • generic-hwe-edge Provides early access to the next generic-hwe kernel.

HWE follows upstream closer, with fewer backports. So faster features, but at the price of more change. Normally hwe only gets upgraded to the next Ubuntu release's kernel, but the edge variants have newer versions. Often three versions total to choose from. (Note these are not necessarily the stable or longterm versions from kernel.org, distros do their own kernel maintenance.)

For some situations, the latest version of Ubuntu makes sense even if not a LTS. Especially if other software needs updating. Of course, non-LTS releases need major version upgrades faster.

In practice, to find what is available search packages.ubuntu.com for linux-generic and apply filters for suite and architecture.

John Mahowald
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  • Thank you John, your answer was super helpful with links to the information that Canonical does provide as well as filling in the gaps of what they don't provide. Combined, I was able to understand this process a lot better. I ended up going with `linux-image-5.11.0-22-generic`. Knowing that this wasn't the same numbering as kernel.org and why precisely closed the gaps in my head. Thank you so much! – Brian Topping Jun 26 '21 at 04:28